Advancements in digital video technology have resulted in the proliferation of computer-based video products in commercial and consumer markets. The continuing development of new generations of high-speed microprocessors has enabled software developers to develop motion video applications for use on the personal computer. One such emerging category of motion video applications includes software-implemented video editing systems.
Prior to exploiting the processing capability of desktop computers to facilitate the video editing process, a traditional editing approach typically involved physically splicing taped segments of video under a microscope using very expensive equipment. More recently, computer-based video editing systems were developed that increased the efficiency of the editing process, but provided limited functionality due to the inherent linear nature of such early computer-based editing systems. In general, such linear editing solutions required a user to constantly seek from one portion of a video tape to another portion in order to view various non-sequential segments of a video program. It can be appreciated that a linear editing approach is very time-consuming and severely limits the degree to which various special effects, such as dissolves and wipes, can be effectuated.
Presently, a number of hardware and software manufacturers have developed non-linear type video editing tools that provide a variety of special effects. With the advent of more powerful microprocessors and high-bandwidth bus architectures, desktop video editing has been made available to the consumer market. Such personal computer-based editing systems, however, generally provide only a limited degree of functionality and capability in comparison to their expensive, high-end mainframe counterparts.
Various software applications have been developed to play motion video files on personal computer systems. Two very popular desktop video playback applications are QuickTime.TM., which operates on Macintosh.RTM. compatible personal computers, and Video for Windows.RTM., which operates on AT-type compatible personal computers. Although these and other similar products provide a means for playing back motion video files on a personal computer, consumers and other video program developers continue to seek video editing tools to enable them to produce multimedia video applications efficiently and at a relatively low cost. A number of video editing software tools have been developed for consumer-grade personal computers. These systems generally employ digital video compression techniques to digitize and compress analog video in order to significantly reduce the amount of hard disk memory allocated for storing video files, and to permit random access to desired locations in a video program.
A conventional desktop video editing system typically provides a multimedia developer with a number of editing capabilities, including various special effects, transitions, and the capability to effectively splice together various independent video and audio clips. Such systems permit the development of multimedia applications that are often designed to follow a pre-established script or storyboard. A multimedia developer may also produce an interactive multimedia application in which a user can, to some degree, control the progression of application playback.
A traditional approach to providing a user-interactive interface for navigating a multimedia application storyboard involves prompting a user as to the existence of a deviation point in the presentation, and presenting available navigation options upon reaching the deviation point, typically by presenting to the user a list of question on the video display. Depending on the user's response to the questions presented on the display, the desired deviation from the current presentation or, if selected, continuation of the current presentation is effectuated.
It can be appreciated that this and similar methods for prompting a user as to the existence of a deviation point or other user-actuatable function through the interactive interface interrupts the continuity of the presentation, requires the user to read the displayed prompt message and respond accordingly, and generally disrupts the overall flow and effectiveness of the multimedia presentation.
Another significant deficiency associated with conventional desktop video editing systems concerns the inherent difficulty of modifying data associated with the video and audio signal components of a multimedia application. More specifically, a multimedia information signal or bitstream is typically comprised of a video signal portion, and audio signal portion, and a data signal portion which are multiplexed or interleaved into a composite multimedia bitstream. The video signal portion represents the visual content of the multimedia bitstream, while the audio signal portion represents the audio content of the multimedia bitstream. The data signal portion generally represents instructions and other information which, when interpreted by a computer, effect various multimedia functions, such as visual prompts to a user and effecting diversions from a current presentation.
Generally, the video, audio, and data signal portions are interleaved or multiplexed into an integral multimedia bitstream, and generally organized in accordance with a proprietary format. The incorporation of the data signal portion into a composite multimedia bitstream significantly increases the difficulty of efficiently modifying a multimedia application. The instructions associated with diversions, prompts, and other interactive functions in a multimedia application, which are typically defined in the data signal portion of the multiplexed multimedia bitstream, are generally indistinguishable and inaccessible from other signal portions, thereby virtually precluding the opportunity of efficiently modifying the data signal portion. Any such modifications may, if at all, be accomplished by recreating the effected portion of a multimedia application.
There exist a keenly felt need in the digital video industry for an intuitive technique for prompting a user as to the existence of an interactive function during a multimedia presentation without distracting the user or interrupting the continuity of the multimedia presentation. There exists a further need for a video editing format that permits access to, and efficient modification of, the data signal portion of a multimedia bitstream. The present invention fulfills these and other needs.